Various forms of sliding vane rotary fluid motors heretofore have been provided and many of these previously known sliding vane fluid motors have been constructed for selective rotation in either direction. However, sliding vane rotary motors often include springs to yieldingly bias the vanes thereof toward outermost limit positions and while the operation of such springs is efficient during outward movement of the vanes, it causes excessive wear on the outer ends of the vanes and on the associated rotor cavity walls during inward movement of the vanes. Accordingly, a need exists for a sliding vane rotary motor equipped with rotor mounted structure whereby outward movement of the vanes relative to the motor may be effected by means other than springs and inward movement of the vanes relative to the rotor will not be resisted by spring pressure.
Examples of various forms of sliding vane rotary motors including some of the general structural and operational features of the instant invention are disclosed in U.S. Pat. Nos. 836,768, 889,092, 1,006,035, 2,233,269, 2,345,561, 3,323,501, 3,343,782, 3,451,381 and 3,952,709.